1. Field of the Invention
This invention relates generally to snow and sleet detectors and, more particularly to snow and sleet detectors having improved performance in wet snow conditions.
2. Description of the Prior Art
Detectors similar to that described in U.S. Pat. No. 3,157,800 issued to the applicant on Nov. 17, 1964, have proved useful in detecting snow and sleet conditions at locations such as railroad switches and electrically heatable sidewalks or ramps. The detectors can generate a remote indication of a potentially dangerous condition and/or actuate electrical heaters or other automatic safety equipment.
However, difficulties have been experienced in known snow and sleet detectors described in applicant's above-identified earlier patent, particularly in conditions of wet snow. Under such conditions the snow tends to stick to the rim of the detector and to bridge over the detector head thereby blocking further snowfall from reaching the detector mechanism. This has in some cases required the provision of a separate heater which clamps onto the top of the snow and sleet detector to prevent the buildup of such a snow bridge. But such heaters under many circumstances are completely unsuitable in some applications.